1. Field of the Invention
This invention related generally to robotic grasping devices, and more particularly to an articulated grasping apparatus having opposing digits capable of closing onto an article for the purpose of engaging such an article in order to place or position the article.
2. Description of Related Art
The following art defines the present state of this field:
Sokolow, U.S. Pat. No. 3,981,673 describes an apparatus for transferring parisons from an oven to a blow mold has the capability of straightening up titled parisons and gripping them uniformly without flattening the ends. The apparatus includes a gripper with jaws which open wide when opened, thereby providing an entry space between the jaws for titled parisons as well as an upright parison and which in the closed position form an essentially complete circle about the parison to uniformly grip the same in cooperation with a push piece which moves into the open end of the parison.
Evans et al., U.S. Pat. No. 3,651,958 describes a transfer carriage movable between a station and a machine tool having a pair of work carriers movable independently along intersecting paths operable to pick up a work piece and to deposit in its place another work piece, both at the station and at the machine tool.
Bende, U.S. Pat. No. 3,400,836 describes an apparatus for grasping, holding and transferring a work piece on a high speed production line. The clamp is biased to the closed position to prevent slippage of the work piece during transfer. Cam controls regulate the movement of the clamp from a folded or stored position to a grasping position and then closed and open the clamp at the appropriate time in the cycle of the apparatus.
Panyard, U.S. Pat. No. 5,588,794 provides a gripper for mounting to a distal end of a robotic arm for gripping a work piece having a pair of spaced apart longitudinally extending contoured faces and at least two extending cylindrical bores, each cylindrical bore having an inner surface, the gripper including a base, a pair of spaced apart longitudinally extending stabilizing members each affixed to the base, each of the stabilizing members having an engagement surface adapted to abuttingly engage a respective contoured face of the work piece, at least one pair of opposing clamping arms, each clamping arm being pivotal from a first position wherein the clamping arm is disposed adjacent a respective cylindrical bore to a second position wherein the clamping arm abuttingly engages the inner surface of a cylindrical bore, a pair of biasing cylinder means connected to one of said pair of clamping arms for moving said one clamping arm from said first position to said second position, a pair of spaced apart compliant devices affixed to the base for releasably connecting the base to the distal end of the robotic arm and a control system for selectively controlling the actuation of the biasing cylinders.
Inaba et al., U.S. Pat. No. 4,540,212 describes an industrial robot hand having swing fingers for gripping a work pivotally mounted on a hand base member which is attached to the free end of a wrist unit, said swing fingers being members formed of a sheet metal through a pressing process in a U-shaped cross-section, and said swing fingers having a U-shaped cross-section and a hydraulic actuator linked together with chain pin links.
Asamoto, U.S. Pat. No. 3,945,676 describes a gripping device for use in an industrial robot or manipulator including a pair of clamp arms mounted on a base plate of the device and connected with a clamp arm operating rod through a pair of links and a cylinder-piston assembly having a misgrip detecting mechanism. One of the pair of clamp arms is shorter than the other clamp arm and is provided with an additional clamp arm swingable with respect to the sort clamp arm. The misgrip detecting mechanism is operated by the action of a pressure switch provided in a hydraulic fluid conduit connected between the hydraulic fluid supplying source and a pressure chamber formed within the cylinder-piston assembly. Thus, the gripping device can positively and effectively grip a work piece.
McGill, U.S. Pat. No. 3,125,370 relates to article grippers, and particularly to apparatus for picking up articles such as bottles, containers or the like, transporting them a distance, and then depositing the articles in a second position. The general object of the present invention is to provide novel and improved bottle gripper apparatus characterized by the self-centering action thereof when any of the bottle grippers are moved laterally from their normal centered position. A further object of the invention is to provide a pivotally positioned substantially parallelogram shaped means in the assembly of gripping jaws and associated controls in article grippers and wherein a pair of laterally spaced lost-motion connecting means are present and have associated compressed coil springs urging the lost motion means to the extremities of their positions normally, but with one such lost motion means being adapted to be moved outwardly of the parallelogram when the article grippers are moved laterally to further compress on positioned coil spring means and aid in snapping the means back into a normal centered position when the external force applied thereto is removed.
The prior art teaches similar devices to the instant invention which are useful for similar application. However, the prior art does not teach a grasping device of such compact design and wherein sliding members of the actuated fingers are engaged and movable within the material that makes-up a fluid piston. This inventive concept provides significant advantages in miniaturization, clearance requirements when in use, and simplicity of operation. The present invention fulfills these needs and provides further related advantages as described in the following summary.